Rubber surface non-stick ply turn-up bladder

ABSTRACT

A tire ply end turn-up device comprising an inflatable first rubbery polymer bladder body, a second non-stick rubbery polymer layer on at least a portion of the surface of the bladder body, and fabric between the bladder body and the non-stick surface. The ply turn-up bladder is made by forming an uncured rubbery polymer bladder body, forming a composite of fabric calendared on one side with an uncured non-stick rubbery polymer and on the other with a rubbery polymer that will bond with the bladder body upon curing, applying the composite to at least a portion of the bladder body, and curing the bladder body and composite to form an integral turn-up bladder with a non-stick rubber surface. A rubbery polymer that will bond with the uncured bladder body upon curing is used on the fabric side that contacts the bladder body.

This is a divisional of copending application Ser. No. 07/865,789 filedApr. 7, 1992 now U.S. Pat. No. 5,250,142, as a continuation of Ser. No.558,907, filed Jul. 27, 1990, now abandoned.

BACKGROUND OF THE INVENTION

The invention generally relates to turn-up bladders used in the tirebuilding process. More specifically, the invention relates to bladdershaving non-stick rubber surfaces for turning over uncured tire plys.

Tire building machines use annular inflatable rubber bladders to turn upthe ends of plys of tires. During the turn-up operation, the uncured plymaterial is wrapped around and over the bead rings and against itself.Because the rubber ply material is tacky, the uncured ply materialsticks to itself when the inflatable bladder doubles it over the beadingring.

Turn-up bladders traditionally have been made from vulcanized rubber(natural, synthetic or mixtures of the two) that has the undesirablecharacteristic of sticking to the tacky uncured tire plies when makingcontact with the uncured ply during the turn-up operation. Suchmomentary adhesion is especially destructive because the bladder exertspressure against and, subsequently, away from ply. This adhesion resultsin possible defects to the tire ply and, after periodic use, prematuredeterioration of the bladder surface.

Initial attempts to deal with the problem of the bladder sticking to theply during the tire building operation have met with only limitedsuccess. One early attempt involved applying a layer of non-stick rubberto the portion of the periphery of the bladder body contacting the plyend. Unfortunately, while the non-stick rubber did not stick to the ply,it also did not sufficiently adhere to the bladder body. After repeatedoperations, the non-stick rubber would begin to separate from thebladder body.

A later, alternative approach to the problem is described in U.S. Pat.No. 4,381,331 ("the '331 patent"). That patent teaches replacing thenon-stick surface rubber with a fabric having reduced adhesion touncured rubber. The fabric is embedded in a portion of the bladdersurface. This attempted solution has the disadvantages of the fabricfibers on the bladder surface becoming frayed and of the cordsseparating from the bladder body after extended use.

It is an object of the present invention to provide a bladder having anon-stick rubber surface layer that will have improved adhesion to thebladder body and reduced tendency to separate from the bladder bodyduring use.

It is another object of the present invention to provide a non-stick plyturn-up bladder without exposed fabric cords that could fray or separatefrom the bladder body during use.

It is a further object of the present invention to provide an improvedply turn-up bladder with increased adhesion of a non-stick rubbersurface layer to the bladder body, such that the useful life of thebladder is increased.

It is yet a further object of the present invention to provide a methodof making a bladder having a non-stick rubber surface with theabove-listed desirable characteristics.

SUMMARY OF THE INVENTION

The invention is a ply turn-up bladder comprising an inflatable rubberypolymer bladder body which has a non-stick rubbery polymer surface layersecured to at least a portion of the bladder body's periphery byembedding a fabric between the bladder body and the non-stick rubberypolymer surface layer. The fabric permanently and integrally bonds thenon-stick rubbery polymer surface layer to the bladder body. The plyturn-up bladders preferably utilizes a third rubbery polymer layerbetween the bladder body and the fabric, the third rubbery polymerhaving a different hardness or tackiness characteristics than thebladder body or the non-stick layer.

The present invention also contemplates a method of making the improvedbladder comprising forming an uncured, inflatable bladder body of arubbery polymer and a fabric composite having rubber on both sides. Thecomposite is formed by calendering one side of a fabric sheet with anuncured non-stick rubber polymer and calendering the opposite side ofthe fabric with an uncured rubber polymer capable of permanently bondingwith the bladder body when cured therewith. The composite is applied toa portion of the periphery of the bladder body, and the bladder body andcomposite are bonded together by curing.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of the preferred embodiment of thecompleted non-stick turn-up bladder showing the bladder body and thenon-stick outer surface layer;

FIG. 2 is a perspective view of the intermediate composite that isapplied to the uncured bladder body before curing;

FIG. 3 is a detailed cross-section of the composite shown in FIG. 2;

FIG. 4 is a cross-section of the preferred embodiment shown in FIG. 1;

FIG. 5 is the cross-section of an alternative embodiment of thecompleted non-stick turn-up bladder; and

FIG. 6 is the cross-section of a second alternative embodiment of thecompleted non-stick turn-up bladder.

DESCRIPTION OF THE PREFERRED EMBODIMENT

As shown in FIGS. 1 and 4, the inventive non-stick turn-up bladder 8comprises a bladder body 10, a non-stick rubber outer surface layer 12covering a portion of the bladder body 10, and a textile fabric 14between the bladder body 10 and the non-stick outer surface layer 12.The bladder body 10 may be made of a flexible rubbery polymer,preferably natural rubber, or any other material well known in the art.The bladder body 10 may also have, in its interior, reinforcing meanssuch as a cord fabric or mylar, or any other appropriate material knownin the art.

The fabric 14 between the bladder body 10 and the non-stick outersurface layer 12 is an adhesion treated textile fabric, preferablypolyester cord, but alternatively aramid fiber cord or other materialswhich are extensible in the lateral direction (allowing expansionbetween the cords) and which will adhere to both the bladder body 10 andthe non-stick outer surface layer 12 may be used. As shown in FIGS. 3-5,the fabric 14 consists of many parallel filament cords 16 temporarilyheld together by thread or other means known in the art. The outersurface layer 12 preferably is a non-sticking rubbery polymer such asnitrile blends or any other rubbery material known in the art that willadhere to the fabric material but will not adhere to the types ofuncured rubber normally used in tire plies.

As shown in FIG. 4, the fabric 14 permanently bonds the non-stick outersurface layer 12 to the bladder body 10 at least in part because thefabric is embedded in (and adheres to) the rubber surface layer 30 thatis integrally formed with the bladder body 10. The non-stick surfacelayer 12 in-turn is embedded in the second, opposite side 26 of thefabric 14. Thus, the fabric enables the non-stick surface layer 12 topermanently bond to and become integral with the bladder body 10.

The inventive non-stick bladder is manufactured by forming an annular,uncured inflatable bladder body in a manner well known in the art. Acomposite 20 is independently formed by calendering the first side 22 ofthe fabric sheet 14 with a layer 24 of a rubbery polymer that will bondwith the bladder body upon curing (preferably a blend of natural andnitrile rubber), and calendering the second side 26 of the fabric sheet14 with a layer of a non-stick rubbery polymer 12 (also shown as 28 inFIGS. 2 and 4-6). (The term "calendering" is not intended to be limitedto pressing of a sheet of rubber to a sheet of fabric, but includesskimming and other methods known in the art for applying rubber tofabric.)

After formation of the composite 20, it is applied to the bladder body10 with layer 24 (also shown as 30 in FIGS. 4 and 6) in contact with aportion of the periphery of the bladder body 10 and the non-stick layer28 facing outward. The bladder body 10 and composite 20 are subsequentlycured together, as by heating or other means known in the art. As shownin FIG. 4, the curing integrally forms the layer of the first rubberypolymer layer 24 of the composite 20 with the bladder body 10. Becausethe two opposite layers of rubber are both in contact with the fabric,the layer of the second non-stick rubbery polymer 28 permanently adheresto the fabric 14 and also to the bonding rubbery polymer layer 24 andbladder body 10.

An alternative embodiment of the instant invention is shown in FIG. 5.This embodiment uses an intermediate rubbery polymer layer (shown as 30in FIG. 4) that is the same rubber composition used in the bladder body10. Upon curing, the fabric 14 permanently adheres to the layer of theintermediate rubbery polymer, which becomes indistinguishable from thebladder body 10 (as shown in FIG. 5), and the layer of the non-stickrubbery polymer 28 as previously described.

The alternative embodiment is manufactured by forming the annularinflatable bladder body 10 with an appropriate uncured rubbery polymer.The composite 20 is independently formed by calendering the first side22 of the fabric sheet 14 with a layer of the same rubbery polymer usedto form the bladder body 10 and calendering the second side 26 of thefabric sheet 14 with a layer of the non-stick rubbery polymer 28. Thecomposite 20 is then applied to the bladder body 10 so that the layer ofthe bladder body type rubbery polymer on the composite 20 is in contactwith a portion of the periphery of the bladder body 10. Finally, thebladder body 10 and composite 20 are cured, as by heating or any othermeans known in the art.

The outer, non-stick rubber of the finished bladder may have a smoothsurface, as shown in FIG. 5, or a textured surface, as shown in FIG. 4.A relatively thin layer or skim coat of non-stick rubber on the fabricwill create a non-stick rubbery polymer surface having a desirableribbed texture, without the disadvantages of having an exposed fabricsurface on the bladder. This textured surface also has the advantage ofbeing created without the need for specialized molds or templates. It isanticipated that this surface may further decrease the momentaryadhesion between the finished bladder and the uncured ply.

Because the rubber used for the rubber layer 24 of the composite mayhave lower viscosity than the non-stick rubber used for the outer layer28, curing may cause the one layer to flow through the cords to a largerextent that the other. As shown in FIG. 4, the rubber of inner layer 30has lower viscosity than the non-stick rubber 26, and therefore is shownas having flowed through the fabric 16 and away from the bladder bodymore than the outer rubber 26 flowed toward the bladder body. Themagnitude of this effect will vary depending on the particular rubberypolymers used.

FIG. 6, on the contrary, demonstrates the use of a rubbery polymer layer30 (shown as 24 in FIG. 2 in the uncured state) which has about the sameviscosity as the non-stick rubbery polymer. Curing of that bladder wouldnot result in a disparity of flow of rubbery polymers through the fabric16. Thus, the different rubber materials appear equally divided oneither side of the fabric after curing.

The preferred and alternative embodiments of the instant invention aredescribed above for illustrative purposes only and as required bystatute. It is understood that the invention is not limited to theparticular embodiments described in this specification but may appear indifferent forms utilizing the same inventive concept. The scope of theinvention is not governed by the specific structures contemplated above,but shall be properly judged by the following claims as interpreted byestablished doctrines of claim construction and equivalents.

What is claimed is:
 1. A method of making a ply turn-up bladdercomprising the steps of:forming a bladder body of uncured rubberypolymer; forming a composite of fabric covered on both sides withrubber, one side of the composite having a non-stick rubbery polymer andthe other side having a rubbery polymer capable of permanently bondingwith the bladder body when cured therewith; applying the composite to atleast a portion of the bladder body with bonding rubbery polymer incontact with the body; and curing the bladder body and composite.
 2. Themethod of claim 1, wherein the bladder body and composite are cured byheating.
 3. The method of claim 1, wherein the bonding rubbery polymeris the same rubbery polymer as the bladder body.
 4. The method of claim1, wherein the composite is formed by calendering the fabric on bothsides with the rubbery polymers.
 5. A method of making a ply turn-upbladder comprising the steps of:forming a bladder body of first uncuredrubbery polymer; forming a composite of fabric covered on both sideswith rubbery polymers by calendering one side with a second non-stickrubbery polymer and the opposite side with a third uncured rubberypolymer; applying the composite to at least a portion of the bladderbody third rubbery polymer side in contact with the bladder body; andcuring the bladder body and composite; whereby the composite with outernon-stick rubbery polymer surface is integrally formed with the bladderbody.
 6. The method of making a ply turn-up bladder of claim 5, whereinthe first and third rubbery polymers are the same.
 7. A method of makinga turn-up bladder having an outer surface for contacting an uncured tireply, the method comprising the steps of:forming a bladder body of afirst uncured rubbery polymer, the bladder body having an inner and anouter surface; forming a composite of fabric covered on one side with alayer of an uncured second rubbery polymer and on the other side with alayer of an uncured third rubbery polymer, the first and second rubberypolymers being selected such that the second rubbery polymer in a curedstate is less adhesive than the first rubbery polymer in a cured stateto uncured tire ply; and, applying the composite to at least a portionof the bladder body with the third rubbery polymer layer in contact withthe outer surface of the bladder body.
 8. The method of claim 7, whereinthe third rubbery polymer layer is uncured when the composite is appliedto the bladder body.
 9. The method of claim 8, further comprising thestep of adhering the third rubbery polymer layer to the bladder body atleast partially by curing.
 10. The method of claim 9, wherein the curingis accomplished at least partially by heating.
 11. The method of claim9, wherein the third rubbery polymer is selected such that the thirdrubbery polymer is more adhesive than the second rubbery polymer to thefirst rubbery polymer upon curing.
 12. The method of claim 7, whereinthe third rubbery polymer is the same as the first rubbery polymer. 13.The method of claim 7, wherein the composite is formed by calendering alayer of uncured second rubbery polymer on one side of the fabric and alayer of uncured third rubbery polymer on the other side.
 14. The methodof claim 7, wherein the fabric is treated to adhere to both the secondrubbery polymer layer and the third rubbery polymer layer.